Electric multi-phase machines are utilized in a wide variety of applications. As used herein, the term “multi-phase” refers to three or more phases, and can be used to refer to electric machines that have three or more phases.
For example, many hybrid/electric vehicles (HEVs) include a machine drive system (sometimes also referred to as an electric traction drive system) that includes as alternating current (AC) electric machine that is driven by an inverter module. The inverter module is supplied with power from a direct current (DC) power source, such as a storage battery. An AC cable can be used to couple terminals at the windings of the AC electric machine to corresponding terminals at the inverter sub-modules of the inverter module. Each inverter sub-module includes a pair of switches. Switching signals are applied to each pair of switches in a complementary manner to convert the DC power to AC power that drives the AC electric machine, which in turn drives a shaft of HEV's drivetrain.
In some situations, an AC-to-chassis fault can occur at a motor winding of the electric machine (or the terminal it is connected to), at the inverter sub-module (or the terminal it is connected to or in one of the elements of an inverter sub-module), or at any point along the AC cable that couples the terminals of the machine to terminals of the inverter module.
It would be desirable to provide circuitry that can help protect the inverter module from high magnitude of fault currents that flow when an AC-to-chassis fault happens. Other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.